Spontaneous Self-Assembly of Fully Protected Ester 1:1 [alpha/alpha-N-alpha-Bn-hydrazino] Pseudodipeptides into a Twisted Parallel beta-Sheet in the Crystal State

Abstract : Previous studies have, demonstrated that amidic alpha/beta-pseudodipeptides, 1:1 [alpha/alpha-N-alpha-Bn-hydrazino], have the ability to fold-via a succession of gamma-turn (C-7 pseudocycle) and hydrazinoturn in CDCl3 solution, their amide terminals enabling the formation of an intramolecular H-bond network. Despite their lack of a primary amide terminals allowing the formation of the hydrazinoturn, their ester counterparts 1-4 were proven to self-assemble into C-6 and C-7 pseudocycles by intramolecular H-bonds in solution state and into an uncommon twisted parallel beta-sheet through intermolecular H-bonding in the crystal state to form a supramolecular helix, with eight molecules needed to complete a full 360 degrees rotation. Such self organization (with eight molecules) has only been observed in a specific alpha/alpha-pseudodipeptide, depsipeptide (Boc-Leu-Lac-OEt). Relying on IR absorption, NMR, X-ray diffraction, and CD analyses, the aim of this study was to demonstrate that stereoisomers of ester 1:1 [alpha/alpha-N-alpha-Bn-hydrazino] pseudodipeptides 1-4 are able to self-assemble into this beta-helical structure. The absolute configuration of the asymmetric C-alpha-atom of the alpha-amino-acid residue influences the left-or right-handed twist without changing the pitch of the formed helix.
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Article dans une revue
Journal of Organic Chemistry, American Chemical Society, 2016, 81 (19), pp.9037-9045. 〈10.1021/acs.joc.6b01680〉
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Soumis le : mercredi 29 mars 2017 - 10:46:36
Dernière modification le : mardi 24 juillet 2018 - 16:43:01

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Eugenie Romero, Ralph-Olivier Moussodia, Alexandre Kriznik, Emmanuel Wenger, Samir Acherar, et al.. Spontaneous Self-Assembly of Fully Protected Ester 1:1 [alpha/alpha-N-alpha-Bn-hydrazino] Pseudodipeptides into a Twisted Parallel beta-Sheet in the Crystal State. Journal of Organic Chemistry, American Chemical Society, 2016, 81 (19), pp.9037-9045. 〈10.1021/acs.joc.6b01680〉. 〈hal-01497720〉

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